Structural damage leading to collapse has resulted in injuries and death to rescue workers and others within the vicinity of the collapse. In many rescue operations, the condition of the structure plays a relatively minor role in deciding when and how to enter the structure, particularly if human lives are in danger. The typically complex nature of how damage propagates and may ultimately weaken a structure has made it very difficult to predict imminent collapse. Visual inspections alone, especially during firefighting operations, cannot guarantee detection of mechanisms that could lead to collapse and loss of life. A need exists, therefore, for a technical approach that can monitor structures that are severely damaged and in danger of collapse.
Collapse monitoring, however, is based on the premise that the degree of damage to the structure is so severe that continued exposure to the current loading condition will lead to imminent collapse. A burning structure is, by definition, already damaged due to the fire. The ability to simply detect and track damage mechanism due to fire does not provide a mechanism that will detect impending collapse.
Structural damage detection research is best characterized as using nondestructive testing techniques to determine the behavior of response characteristics under known loading conditions. The selection of the particular testing technique, however, plays a large role in the effectiveness of the detection technique. Prior art damage detection devices and methodologies do not provide nondestructive testing devices and methodologies.
Existing devices that detect damage in structures rely mainly on approaches that induce high frequency or acoustic energy into the structure or that use monitoring devices at critical locations within a structure.
U.S. Pat. No. 5,675,809 to Hawkins, for example, discloses a passive strain gauge that can be mounted to buildings. The gauge emits acoustic waves commensurate with load bearing stress exerted on a building in earthquakes and the like. Similarly, U.S. Pat. No. 5,404,755 to Olson, et al., disclose a method of testing stress in wood and other products using ultrasonic frequencies.
These types of gauges and methodologies operate over a wide frequency range, well beyond those associated with structural resonances. As such, they are not effective in isolating structural response behavior and do not possess the sensitivity required for collapse monitoring.
U.S. Pat. No. 6,138,516 (to Tillman) discloses a device that monitors the amount of shock applied to a location on a structure. The device is a shock detector and utilizes an accelerometer adapted to generate a rectified signal that is compared to a threshold level to produce a high voltage state. Detection of shock on a structure, however, cannot be used for monitoring structural response leading to lapse, particularly since Tillman utilizes a set threshold level below which the device remains in a low voltage state
The need for determining impending structural failure is significant. The present invention provides a new and unique device and method for determining structural damage and imminent failure, which will help to prevent injuries and save the lives of rescue workers and persons within the realm of a building collapse.
It is, therefore, an objective of this invention to provide a system and method for determining the onset of collapse of a structure, detecting the progression of the collapse mechanism and detecting severely reduced structural integrity in the aftermath of a condition impacting the structure.
It is another objective of this invention to provide a system that utilizes at least one accelerometer that is capable of measuring acceleration responses down to zero Hz.
It is another objective of this invention to provide a system and method for detecting collapse of a structure using at least one accelerometer that is capable of measuring acceleration responses in at least one axial (x, y, or z) direction, utilizing the device of the present invention.
It is another objective of this invention to provide a system that utilizes a device that can be attached on an exterior surface away from damage conditions where the device is attached perpendicular to the direction of the portion of the structure being monitored.
It is yet another objective of this invention to provide a system that utilizes a device that is lightweight, waterproof and capable of withstanding temperatures of up to 1900xc2x0 F.
It is yet another objective of this invention to provide a system that utilizes a device that operates on an independent power source.
It is yet another objective of this invention to provide a system that utilizes an outside power source including a building""s power source that is being monitored for collapse conditions.
It is yet another objective of this invention to provide a system that utilizes analog and/or digital signals to evaluate data transmitted to a remote receiver of the system.
It is yet another objective of this invention to provide a system that utilizes computer technology to evaluate the transmitted signals to determine and detect collapse situations.
It is yet another objective of this invention to provide a system that utilizes wired and wireless communications to transmit signals from the device to the remote receiver.
These and other objects of this present invention are met by this invention as described herein below.